C# Essentials

Access Modifiers

To promote encapsulation, a type or type member may hide itself from other types or other assemblies, by adding one of the following five access modifiers to the declaration:

public

The type or type member is fully accessible. This is the implicit accessibility for enum members (see Section 2.12) and interface members (see Section 2.10).

internal

The type or type member in assembly A is accessible only from within A. This is the default accessibility for nonnested types, so may be omitted.

private

The type member in type T is accessible only from within T. This is the default accessibility for class and struct members, so it may be omitted.

protected

The type member in class C is accessible only from within C or from within a class that derives from C.

protected internal

The type member in class C and assembly A is accessible only from within C, from within a class that derives from C, or from within A. Note that C# has no concept of protected and internal, where a type member in class C and assembly A is accessible only from within C or from within a class that derives from C and is within A.

Note that a type member may be a nested type. Here is an example that uses access modifiers:

// Assembly1.dll using System; public class A { private int x=5; public void Foo( ) {Console.WriteLine (x);} protected static void Goo( ) {} protected internal class NestedType {} } internal class B { private void Hoo ( ) { A a1 = new A ( ); // ok Console.WriteLine(a1.x); // error, ...